High-Contrast Grating VCSELs

Abstract

Recent advances in a single-layer 1-D high-index-contrast subwavelength grating structure are reviewed. Its incorporation into a vertical-cavity surface-emitting laser (VCSEL) structure enabled simple fabrication, lithographically defined polarization control and large aperture, single-transverse-mode control. Extraordinarily large fabrication tolerance is demonstrated with <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm20\%$</tex></formula> variation of the high-contrast grating (HCG) critical dimension. Emission wavelength of HCG-VCSEL varied 0.2% with a 40% change in lithography linewidth. Tunable VCSELs are fabricated using HCG, which led to a 8000 times reduction in the tunable mirror size and 160 times improved tuning speed of 63 ns. This configuration will open the door for a wide spectrum of optoelectronic devices in large wavelength regimes.